Hydraulic interrupter safety system and method

ABSTRACT

A system and method for interrupting a Global Navigation Satellite System (GNSS)-based automatic steering mode of a hydraulic steering system on a vehicle. When a steering wheel is manually turned by an operator, pressurized hydraulic fluid from a steering directional control valve activates an interrupter having an interrupter valve. The interrupter valve blocks pressurized field flow to the automatic steering system, thus overriding automatic steering and giving the operator full manual steering control via the steering wheel. The hydraulic interrupt system is mechanical with no electronic elements.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. application Ser. No.14/579,919, filed Dec. 22, 2014 which claims priority to U.S.Provisional Patent Application No. 61/919,366, filed Dec. 20, 2013,which are all incorporated herein by reference in their entirities.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to vehicle steering, and inparticular to a hydraulic safety interrupter for automatic steering(“autosteer”) systems, which can use sensors including Global NavigationSatellite System (GNSS), and other guidance and navigation receivers andequipment.

2. Description of the Related Art A. GNSS-Based Vehicle GuidanceBackground

The use of sensors for automating vehicle guidance and machine controlhas significantly advanced these fields and enabled a number ofapplications, including many in agriculture, transportation and otherindustries. For example and without limitation, GNSSs are commonly usedfor guidance, navigation and machine control. GNSSs include the GlobalPositioning System (GPS) and other satellite-based systems. Various GNSSreceivers are available for aviation, marine and terrestrial vehicles.The GNSS information provided by such receivers can be processed andused for navigation. In more sophisticated systems, vehicle guidance canbe automatically controlled using such information. For example, apredetermined travel or flight path can be programmed into an on-boardcomputer. The vehicle guidance system can automatically maintainappropriate course parameters, such as course, heading, speed, altitude,end-of-row U-turns, etc. Control system, feedback theory, and signalfiltering techniques can be used to interactively anticipate (withhigher order systems) and compensate for course deviations andnavigation errors. Such sophisticated autopilot and automatic steeringsystems tend to involve powerful computers and complex flight andsteering controls integrated with manual controls.

Accurate vehicle guidance and equipment control are important objectivesin agricultural operations generally and agricultural equipmentspecifically. For example, cultivating, tilling, planting, spraying,fertilizing, harvesting and other farming operations typically involvespecialized equipment and materials, which are operated and applied bymaking multiple passes over cultivated fields. Ideally, the equipment isguided through accurately-spaced passes or swaths, the spacing of whichis determined by the swath width of the equipment.

GNSS technology advanced the field of agricultural guidance by enablingreliable, accurate systems which are relatively easy to use. GNSSguidance systems are adapted for displaying directional guidanceinformation to assist operators with manually steering the vehicles. Forexample, the Outback steering guidance product line was developedprimarily for agricultural applications. Current GNSS-based productsinclude the Outback S3, the eDrive TC and the eDrive X™ which areavailable from Outback Guidance (www.outbackguidance.com) and aremanufactured by AgJunction, Inc. (www.agjunction.com) of Hiawatha, Kans.These products are covered by U.S. Pat. No. 6,539,303 and No, 6,711,501,which are incorporated herein by reference. They include on-boardcomputers which can be programmed for steering vehicles through variousstraight-line and curved (“contour”) patterns. An advantage of thissystem is its ability to retain field-specific cultivating, planting,spraying, fertilizing, harvesting and other patterns in memory. Thisfeature enables operators to accurately retrace such patterns. Anotheradvantage relates to the ability to interrupt operations for subsequentresumption by referring to system-generated logs of previously treatedareas.

The OUTBACK S™ GNSS guidance system provides the equipment operatorswith real-time visual indications of heading error with a steering guidedisplay and crosstrack error with a current position display. Theyrespectively provide steering correction information and an indicationof the equipment position relative to a predetermined course. Operatorscan accurately drive patterns in various weather and light conditions,including nighttime, by concentrating primarily on such visual displays.Significant improvements in steering accuracy and complete fieldcoverage are possible with this system.

Another type of GNSS vehicle guidance equipment automatically steers thevehicle along all or part of its travel path and can also control auagricultural procedure or operation, such as spraying, planting,tilling, harvesting, etc. Examples of such equipment are shown in U.S.Pat. No. 7,142,956, which is incorporated heroin by reference. U.S. Pat.No. 7437,230 shows satellite-based vehicle guidance control in straightand contour modes, and is also incorporated herein by reference.

GNSS guidance systems and equipment are distinguished by their vehiclepath configuration capabilities. Initially, straight-line AB (i.e.,between points A and B) guidance consists of multiple, parallel straightlines, which are separated by the swath widths of the vehicles. Straightline AB guidance is ideally suited for rectangular fields andcontinuously-repeating, parallel swathing.

Non-rectangular and terraced fields typically require curvilinearvehicle paths that follow the field perimeters and the terracedelevation contours. Contour guidance systems and methods were developedto accommodate such field conditions using GNSS coordinates to definecurvilinear vehicle paths. See, for example, Korver U.S. Pat. No.5,928,309. GNSS positions can be logged on-the-fly at intervals of, forexample, 0.20 seconds. Contour guidance can be accomplished bycomputer-generating each subsequent pass from the GNSS-defined previouspuss and a user-entered swath width.

Another type of GNSS contour guidance equipment outputs guidance signalsrelative to the edges of all previously logged swaths. Such loggedswaths typically correspond to field areas where operations, e.g.spraying, have already been carried out. See, for example, U.S. Pat. No.6,5.39,303 and U.S. Pat. No. 6,711,501, which are assigned to a commonassignee herewith and are incorporated herein by reference.

Automatic steering accommodates “hands off” operation, taking intoaccount vehicle operating parameters, such as turning radii, speeds,swath widths, etc. Appropriate machine control functions, such asimplement steering and spray boom control, can also be automated.

B. Manual-Automatic Steering Interface

Although agricultural operations have utilized robotic equipment withouthuman operators on-board, standard practice is to provide an operatorwith the ability to override the automatic steering system. For example,some automatic steering systems will disengage when operator input,e.g., via steering wheel, is sensed. On-board computers can detect suchmanual turning inputs and issue appropriate output commands fordisengaging auto-steering functions. GNSS-guided automatic steering canbe accomplished with hydraulic valve blocks retrofit on existingvehicles, or installed as original equipment in new vehicles. GNSSreceivers provide positioning and navigation data, which can beprocessed by on-board microprocessors for steering and other vehiclecontrol functions. An advantage of the present invention is to provide ahydraulic steering interrupter which is manually-activated and isindependent of the automated, computerized steering controls. Heretoforethere has not been available a hydraulic steering interrupter with theadvantages and features of the present invention.

SUMMARY OF THE INVENTION

In the practice of the present invention, an interrupter is provided fora hydraulic steering system on a vehicle, which can utilize GNSS-basedauto steering. The interrupter is preferably positioned upstream of anauto-steering hydraulic valve block, and activates automatically when asteering wheel is manually turned by the operator. The interruptersenses a pressure signal from the vehicle manual steering and interrupts(i.e., blocks) pressurized hydraulic fluid flow to the automaticsteering input valve, thus canceling the automatic steering command andgiving the operator full manual steering control via the steering wheel.

BRIEF DESCRIPTION OP THE DRAWINGS

FIG. 1 is a perspective view of a vehicle, such as a tractor, equippedwith a hydraulic interrupter in a GNSS-based automatic steering system,embodying an aspect of the present invention.

FIG. 2 is a block diagram of a closed center steering system including ahydraulic interrupter embodying an aspect of the present invention.

FIG. 3 is a block diagram of an open center steering system including ahydraulic interrupter comprising an alternative aspect of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS I. Introduction andEnvironment

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. Therefore, specific structural and functional derails disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure.

Certain terminology will be used in the following description forconvenience in reference only and will not be limiting. For example, up,down, front, back, right and left refer to the invention as oriented inthe view being referred to. The words “inwardly” and “outwardly” referto directions toward and away from, respectively, the geometric centerof the embodiment being described and designated parts thereof. Saidterminology will include the words specifically mentioned, derivativesthereof and words of similar meaning.

Without limitation on the generality of useful applications of thepresent invention, a hydraulic interrupter 21 is provided in a steeringcontrol system 2 on a vehicle 1, which can comprise a tractor equippedwith a Global Navigation Satellite System (GNSS) 13. The GNSS system 13includes a receiver 5 which can be connected to a pair of antennas 9 forvector directional guidance in a horizontal plane based on differencingthe signals received at the respective antennas 9. Such directionalguidance techniques are used for obtaining a vehicle heading in an X-Y(horizontal) plane, even with the vehicle stationary. A guidance centralprocessing unit (CPU) 7 is connected to the receiver 6 for processingthe GNSS positioning signals and outputting guidance signals to thesteering control system 2 for auto-steering the vehicle 1. The vehicle 1can also be equipped with a tow-behind implement, which can also beprovided with GNSS-based control interfacing with the vehicle steeringcontrol system 2. For example, implement-steering can provide advantagesin certain agricultural and other operations.

II. Closed Center Embodiment Steering Control System 2

The steering control system 2 embodying the present invention can beinstalled in various vehicles with manual controls, such as a steeringwheel 8, and an electric-hydraulic power steering subsystem 4 forassisting manual steering and for primarily steering the vehicle inautomatic guidance operating modes (i.e., “auto-steer”). Theelectric-hydraulic steering subsystem 4 is adapted for coupling to aguidance system, such as the GNSS-based guidance system 13 describedabove. The steering subsystem 4 includes a hydraulic interrupter 21 withan interrupter valve 22 adapted for manually overriding or interruptingthe electric-hydraulic steering subsystem 4 and returning control to anoperator via the steering wheel 8. The power steering subsystem 4 can behydraulic, electric-over-hydraulic, pneumatic, etc.

The steering control system 2 includes a steering directional controlvalve 6 connected to the steering wheel 8. A steering priority valve 10connects the steering directional control valve 6 to a pump 11 mountedon the vehicle 1. In an embodiment of the present invention, thesteering directional control valve 6 has a “closed center” configuration(FIG. 2). A load sense line 15 extends from the steering directionalcontrol valve 6 to a load sense shuttle valve 24 and the steeringpriority valve 10 via a “T” connection 25. The load sense line 15activates the interrupter valve 22 by detecting or “sensing” greaterhydraulic pressure front the steering directional control valve 6signaling an operator turning a steering wheel 8 and thus manuallytaking over the vehicle steering. An “override” condition thus occurs,interrupting the automatic steering operation by interrupting thehydraulic fluid flow to the proportional flow control directional valve18.

Hydraulic lines 12 connect the steering directional control valve 6 torespective right and left load holding valves 14R, 14L, which areadapted for maintaining certain fluid pressure levels in theelectric-hydraulic power steering subsystem 4. The system 4 steers thevehicle 1 via a double-acting hydraulic cylinder 28, which can linkdirectly to the vehicle steering gear. A shuttle valve 16 is positionedbetween the load holding valves 14R, 14L. A proportional flow controldirectional valve 18 receives a constant flow of hydraulic fluid via apressure compensating valve 20. The pressure drop across thecompensating valve 20 is maintained relatively constant. The interruptervalve 22 is located between the pressure compensating valve 20 and anenabling valve 26, which is solenoid-activated by the GNSS-basedsteering subsystem 4. The interrupter valve 22 is spring-loaded formaintaining an open position until an override closes it or blockspressure flow to the auto-steering subsystem 4. Such an override signaloriginates with the steering priority valve 10 at the T connect 25,which acts on a load sense shuttle valve 34 The load sense shuttle valve24 provides an input to the pump 11 for varying the displacement asnecessary to accommodate the steering system loads. For example, in theconfiguration shown, the load sense shuttle ball would move to the right(FIG. 2) for manual steering. In an automatic steering mode (i.e.,enable valve 26 open), the hall would be in the left position, Hydraulicfluid is pumped from and returned to a tank 17 having a check valve 29.

III. Open-Center Alternative Embodiment Steering Control System 102(FIG. 3)

An open-center steering control system 102 comprising an alternativeembodiment of the present invention is shown in FIG. 3. The open centerhydraulic circuit utilizes a continuous flow of hydraulic fluid, whichis returned to the tank 117 through an “open center” of a steeringdirectional control valve 106 connected to and controlled by a steeringwheel 108. The control system 102 includes an auto-steer subsystem 104,a steeling priority valve 110, a pump 111, and hydraulic lines 112,which have similar functions to the corresponding components describedabove. An interrupter valve 122 is provided for interrupting the fluidflow like the interrupter valve 22 described above. A “T” connector 125supplies fluid to a pressure compensating valve 120. An enable valve 126connects to the interrupter valve 122. A hydraulic interrupter 121comprises the interrupter valve 122 and other components connectedthereto for interrupting pressure flow to the Cato steer subsystem 104when the steering wheel 108 is moved. A check valve 129 extends betweenlines connecting a pressure side of the circuit and a return to the tank117. Excess flow EF from the hydraulic interrupter valve 122, whichoccurs because of the open center configuration, can be returned to thetank 117.

The system 102 also includes left and right load holding valves 114L,114R, which connect to respective sides of the steeringpiston-and-cylinder unit 128. A shuttle valve 116 connects the fluidinlet sides of the load bolding valves 114L, 114R. A proportional flowcontrol valve 118 is connected to the loud holding valves 114L, 114R andto a directional valve 123.

IV. Conclusion

It is to be understood that the invention can be embodied in variousforms, and is not to be limited to the examples discussed above. Othercomponents can be utilized. For example, various other types of sensorsystems can be utilized in conjunction with hydraulic systems with theadvantages and features of the hydraulic interrupter valve discussedabove.

1. A steering interrupt system for a vehicle, which vehicle includessteerable wheels, a hydraulic steer stem with a pressurized fluid sourceselectively connected to the steerable wheels, a steering directionalcontrol valve connected to the pressurized fluid source, a steeringwheel connected to the steering directional control valve, a steeringactuator selectively connected to the pressurized fluid source via thesteering directional control valve and steerable wheels, and automaticsteering system connected to and automatically controlling the steeringactuator in an automatic steering mode, which steering interrupt systemincludes: said steering interrupt system configured for switching fromsaid automatic steering mode to an interrupt valve mode when saidsteering wheel is turned by an operator; an interrupt valve connected tosaid steering directional control valve and configured for interruptingpressurized fluid flow to said steering actuator in said interrupt mode;said steering directional control valve being connected to said steeringactuator in said interrupt mode; said steering directional control valveproviding pressurized hydraulic fluid to said steer actuator in saidinterrupt mode and thereby controlling said steerable wheels inproportion to movement of said steering wheel by said operator; and saidinterrupt system configured for switching from said interrupt mode tosaid automatic steering mode when said steering wheel is released bysaid operator.